1. Field of the Invention
The present invention relates generally to thermally insulated windows and the like, and more particularly to a gas fill device for multiple pane windows enabling the windows to be charged or recharged with insulating gas in the field or after installation.
2. Description of the Related Art
Constantly increasing energy costs have resulted in correspondingly greater interest in conserving energy to reduce those costs. Virtually all new homes and similar structures are required by building codes to include significant insulation and to have insulated windows and other glass assemblies where applicable. Various professional and industrial organizations, e.g., the National Fenestration Rating Council (NFRC), have developed and set energy conservation standards for the products and services provided by their members.
In many instances and locales, financial incentives are in place to encourage builders and owners to install even more energy efficient assemblies than required by code. For example, rebates have been developed for homeowners installing energy conserving components that meet certain standards. In the case of glass door, window, and other units, rebates of up to one thousand five hundred dollars may be provided for owners and builders installing thermally efficient glass units in the building structure. However, the glass panels and assemblies must have a value of at least E=0.3 in order to qualify.
This can be difficult to accomplish with glass, as glass is a notoriously poor thermal insulating material. As a result, various techniques have been developed and used over the years to optimize the thermal insulation of transparent building panels formed of glass, e.g., windows, doors, skylights, etc. The most common means of increasing the thermal insulation of such glass panels and assemblies is by constructing the panel with two (or more) closely spaced sheets of glass that capture one (or more) insulating spaces or volumes therebetween. The interstitial space(s) between the panes is preferably filled with a dry gas of relatively high molecular weight with good thermal insulating properties, e.g., argon, krypton, xenon, etc., or some mixture thereof as desired.
In order to meet the standards imposed by various governmental agencies and professional groups, such multiple pane assemblies must be constructed, sealed, and filled with insulating gas at the manufacturing site. The intent of such rules is that the sealed unit will maintain its integrity from the point of manufacture to installation. However, this is not always the case, and the regulators and manufacturers recognize this. The main problem is that the glass panes used in the construction of such multiple pane assemblies are relatively thin and fragile, and may easily be broken. Once such a multiple pane assembly has been sealed, the gas pressure contained therein is constant. However, the ambient atmospheric pressure is constantly changing. As a result, multiple pane assemblies are provided with very small diameter breather tubes at the time of manufacture, in order to prevent the panes from breaking due to large differential pressures between the trapped gas within the assembly and the ambient atmosphere.
When multiple pane insulated glass panels are transported, they may undergo significant pressure changes. This is particularly true in mountainous areas of the country, e.g., the Rockies and Sierras. Oftentimes the glass assemblies are assembled and sealed at a site in or near a population center generally located at a relatively low altitude. Yet, the assemblies may have to be transported to a site at a relatively high elevation, or transported over a high mountain pass to their site of installation. The breather tubes installed at the time of manufacture allow the insulating gas to escape to avoid window breakage as the altitude increases and ambient pressure decreases correspondingly, but the breather tube also allows ambient air to flow back into the insulating space as the assembly is transported back to a lower altitude and higher air pressure. Thus, much of the insulating gas is lost during transport, resulting in the insulated glass assembly losing much of its thermal efficiency. In more extreme cases the breather tube may become clogged or crimped, thus preventing the interior volume of the insulated glass assembly from equalizing its internal pressure with the ambient atmosphere. This can often lead to one or more of the glass panes shattering, thus destroying the assembly and requiring it to be shipped back to the manufacturer for new glass, resealing, and refilling with a new charge of insulating gas.
Due to the above problems with transport at high elevation, it can be difficult or impossible in many cases for building contractors and window manufacturers to warranty the required thermal efficiency to qualify for rebates for structures constructed in mountainous areas. This clearly penalizes people living in such areas, and moreover produces structures having less energy efficiency than those constructed at lower altitudes. Yet, the colder temperatures generally occurring at higher altitudes require even greater thermal efficiency from structures in order to conserve energy.
Another problem with such multiple pane thermal glass assemblies is that the seal is never perfect, particularly over a few years or more. Aside from the breather tube venting described above, the seal between the spacer bar and the glass to each side thereof will break down over a period of time. When this occurs, the insulating gas dissipates and air (with some water vapor invariably carried therewith) enters the interstitial space between the glass panes. The problem is most clearly manifested in conditions of relatively large temperature differences between the exterior and interior glass panes, causing condensation to occur on the colder glass pane. When this occurs, much of the original insulating value of the assembly has been lost. The only solution has been to remove the entire glass assembly and replace it with a newly manufactured unit.
Thus, a gas fill device for multiple pane windows solving the aforementioned problems is desired.